The history of playing cards has mostly been a matter of several suits with ranked cards in each suits. The standard 52-card deck is the most familiar version, but there are countless variants. Lots of commercial games follow the same structure, just replacing Clubs and Queens with explorers, rhinos, dwarves, or the colour blue.
This deck is a generic suits-and-ranks deck, with numbered ranks 0 through 15 in each of six different colour suits.
These can be used to play your favourite card games, of course. They can also be used as a component in an existing game when the deck that came with it is so well used as to be marked.
But what it does best is to let you quickly prototype the great game that is lurking in the back corners of your brain. If not in your brain, then in your pancreas. Wherever it is that great games get lodged, it is medically imperative to get that thing out and playtest it today.
All of the cards have ample white space, so that you can scribble labels and instructions to suit the needs of your game.
In addition to the six ranked suits, there are ten yellow suit cards with lots of open space. Use them as wild cards, or mark them up for special purposes.